In 2005 a new interior wall stud called ULTRA STEEL™ was introduced in North America. The technology originated in the UK (invented by Hadley et al) wherein the material was deformed such that it was very difficult to determine the original thickness of the material used. It was reported that ULTRA STEEL™ utilized 0.015″ material thickness versus the industry standard of 0.018″, this provided a 16% savings in weight in an industry where material weight was traditionally a majority of the cost of production. Load tables for the product were provided that verified the capacity of ULTRA STEEL™ to meet the span requirements similar to SSMA (Steel Stud Manufacturing Association) studs. When testing the ULTRA STEEL™ stud to determine its capacity for flexural resistance (by testing the stud only), it did not have the same flexural capacity as a standard 0.018″ stud. It turned out ULTRA STEEL™ used composite assembly system testing with the drywall installed on the studs to reduce deflection when loaded. While ULTRA STEEL™ met certain code requirements for wall deflection based on composite testing, contractors found that the thinner metal being used caused screws to strip when installing drywall. However, the nature of the embossing pattern created a serrated edge on the lip that sometimes cut the fingers of the workers when handling the studs. The new disruptive technology also caused the stud to be weakened in torsion, so it was harder to twist the stud into the track. As a result of the ULTRA STEEL PRODUCT disrupting the market, the stud supply leaders in the industry went into improvement mode and a variety of embossing and rib patterns were developed and introduced by the industry.
Prior art technology to reduce weight use has been developed to provide materials with a variable section such as taught in U.S. Pat. No. 8,646,303. However, this technology is not best suited for a C-Shape stud where the material can be thinnest at the centre of the material strip where the web is located. Alternative technology is shown in U.S. Pat. No. 8,225,581 which provides a variable section with the material being thinnest, as desired, in the centre of the web of the C-shaped stud. To avoid local buckling and premature failure with very thin materials when loads are experienced, the region where there are two layers should be joined requiring an extra function in tooling. Two layers may create a faying area that could potentially attract moisture by virtue of capillary action. Thus two layers are generally not considered a preferred solution.
It would be advantageous to provide a new C-shaped stud that uses less material (than in a conventional) stud but has similar end user characteristics, strength and bending properties compared to the conventional stud.